Rubber composition

Abstract

To provide a rubber composition excellent in damping properties and adhesion to a base material.SOLUTION: A rubber composition comprising a butyl rubber, 50 to 500 parts by weight of a layered or plate-like filler based on 100 parts by weight of the butyl rubber, and a silane coupling agent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a rubber composition. [Background technology]

[0002] Rubber compositions containing butyl rubber have been used to achieve vibration-damping properties. Patent Document 1 (WO 2017 / 018426) discloses a halogenated butyl rubber composition containing 100 parts by mass of halogenated butyl rubber and 3 to 20 parts by mass of liquid unsaturated polybutadiene.

[0003] In order to impart high vibration-damping properties to a rubber composition, it is important that the rubber composition has low hardness (low spring characteristics). One method for reducing the hardness of a rubber composition is to add a large amount of plasticizer to the rubber composition. However, adding a large amount of plasticizer to a rubber composition can reduce the adhesion between the rubber composition and the substrate whose vibration is to be damped by the rubber composition, resulting in the problem of the rubber composition peeling off from the substrate. As a result, the rubber composition is no longer able to damp the vibration of the substrate, and the rubber composition may no longer function as a vibration-damping rubber. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2017 / 018426 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention was made in consideration of the above circumstances. The inventors focused on lamellar or plate-like fillers as components that improve the vibration-damping properties of rubber compositions without reducing hardness with plasticizers, and improved the vibration-damping properties of rubber compositions by combining these fillers with butyl rubber. The inventors also focused on silane coupling agents as components that improve the adhesion of rubber compositions to substrates. That is, the present invention provides a rubber composition that contains lamellar or plate-like fillers and a silane coupling agent, thereby exhibiting excellent vibration-damping properties and adhesion to substrates. [Means for solving the problem]

[0006] The gist and configuration of the present invention are as follows. [1] Butyl rubber, 50 to 500 parts by weight of a layer or plate-like filler relative to 100 parts by weight of the butyl rubber; Silane coupling agent A rubber composition comprising: [2] The rubber composition according to [1] above, wherein the butyl rubber is a halogenated butyl rubber. [3] The rubber composition according to [1] or [2] above, wherein the layered or plate-like filler is mica or kaolin clay. [4] The rubber composition according to any one of the above [1] to [3], wherein the silane coupling agent is a silane coupling agent containing a vinyl group, an amino group, or an epoxy group. [5] The rubber composition according to any one of the above [1] to [4], which contains 0.5 to 20 parts by weight of the silane coupling agent per 100 parts by weight of the butyl rubber. [6] The rubber composition according to any one of the above [1] to [5], further containing an organic solvent and having a solid content concentration of 1 to 50% by weight. [Effects of the Invention]

[0007] It is possible to provide a rubber composition that is excellent in vibration damping properties and adhesion to substrates. DETAILED DESCRIPTION OF THE INVENTION

[0008] The rubber composition of the present invention contains butyl rubber, 50 to 500 parts by weight of a lamellar or plate-like filler per 100 parts by weight of the butyl rubber, and a silane coupling agent. By containing 50 to 500 parts by weight of the lamellar or plate-like filler per 100 parts by weight of the butyl rubber, the vibration-damping properties of the rubber composition can be improved. If the content of the lamellar or plate-like filler in the rubber composition is less than 50 parts by weight per 100 parts by weight of the butyl rubber, the rubber composition will not have sufficient vibration-damping properties. If the content of the lamellar or plate-like filler in the rubber composition is more than 500 parts by weight per 100 parts by weight of the butyl rubber, the filler will not be able to disperse sufficiently in the rubber composition, resulting in the filler dropping out of the rubber composition. Furthermore, acicular particulate fillers such as wollastonite have little effect in improving the vibration-damping properties of the rubber composition, and therefore, a large amount of acicular particulate filler must be added to the rubber composition to impart vibration-damping properties to the rubber composition. In such cases, the addition of a large amount of acicular particulate filler can cause problems such as a decrease in the kneadability of the rubber composition or precipitation of the filler in a rubber composition containing an organic solvent. Therefore, in terms of vibration damping, rubber compositions containing acicular particulate fillers are inferior to compositions containing layered or plate-like fillers, making acicular particulate fillers undesirable. Furthermore, the rubber composition can improve adhesion between the rubber composition and the substrate by containing a silane coupling agent. As a result, the rubber composition of the present invention can achieve both excellent vibration damping and adhesion. The rubber composition of the present invention may be either an uncrosslinked or crosslinked rubber composition, but the rubber composition of the present invention is preferably an uncrosslinked rubber composition. When the rubber composition is an uncrosslinked rubber composition, heat application is not required, and vibration damping properties can be imparted to substrates that cannot be heated.

[0009] The butyl rubber is preferably halogenated butyl rubber. Halogenated butyl rubber is butyl rubber into which halogen atoms such as chlorine atoms and bromine atoms have been introduced, and can provide the butyl rubber with excellent heat resistance. The halogen content in the halogenated butyl rubber is not particularly limited, but can be 1.0 to 2.5% by weight. The halogenated butyl rubber is not particularly limited, but commercially available halogenated butyl rubbers can be used, such as CIIR 1066 and BIIR 2244 manufactured by ENEOS Materials Corporation.

[0010] The layered or plate-like filler is preferably mica or kaolin clay. The layered or plate-like nature of the filler can be confirmed by observing a micrograph of the filler's cross section using a scanning electron microscope (SEM). Examples of layered fillers include at least one material selected from the group consisting of graphite, montmorillonite, nontronite, beidellite, bentonite, vermiculite, mica, calcined clay, molybdenum disulfide, boron nitride, and talc. Examples of plate-like fillers include at least one material selected from the group consisting of kaolin, silica, alumina, boehmite, graphite, and talc. The layered or plate-like filler is not particularly limited, but commercially available layered or plate-like fillers can be used, such as A-11 manufactured by Yamaguchi Mica Co., Ltd., and kaolin manufactured by Hyogo Clay Co., Ltd., as a plate-like filler.

[0011] The silane coupling agent is preferably a silane coupling agent containing a vinyl group, an amino group, or an epoxy group. The rubber composition preferably contains 0.5 to 20 parts by weight, more preferably 1 to 15 parts by weight, of the silane coupling agent per 100 parts by weight of the butyl rubber. The vinyl silane coupling agent containing a vinyl group is not particularly limited, and examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane, and p-styryltrimethoxysilane. The amino silane coupling agent containing an amino group is not particularly limited, and examples thereof include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and N-phenyl-3-aminopropyltrimethoxysilane. The epoxy silane coupling agent containing an epoxy group is not particularly limited, and examples thereof include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. Commercially available silane coupling agents may also be used, and examples of silane coupling agents that can be used include KBM-903 (3-aminopropyltriethoxysilane), KBM-403 (3-glycidoxypropyltriethoxysilane), and KBM-1003 (vinyltrimethoxysilane), manufactured by Shin-Etsu Chemical Co., Ltd.

[0012] The rubber composition further contains an organic solvent, and the solids concentration of the rubber composition (the concentration of all components constituting the solids in the rubber composition) can be 1 to 50% by weight. The organic solvent is not particularly limited as long as it can dissolve the components of the rubber composition, and examples thereof include non-polar solvents such as toluene, xylene, hexane, and cyclohexane. By containing an organic solvent in the rubber composition, the rubber composition can be easily handled as a rubber cement, and can be suitably applied to a desired substrate. Furthermore, since the rubber composition of the present invention has excellent adhesion to a substrate, the rubber composition applied as a rubber cement can maintain excellent adhesion to a substrate even after drying and removing the organic solvent.

[0013] The rubber composition may contain various known additives such as rubber reinforcing agents, antioxidants, processing aids, foaming agents, foaming aids, colorants, dispersants, flame retardants, tackifiers, and release agents as appropriate, as long as the object of the present invention is not impaired. Note that the rubber composition may contain a plasticizer, but from the viewpoint of improving adhesion to a substrate, it is preferable that the rubber composition does not contain a plasticizer.

[0014] The rubber composition can be prepared as a compound by kneading its components (butyl rubber, layered or plate-like filler, silane coupling agent, etc.) using a kneading machine such as an intermix, kneader, or Banbury mixer, or an open roll, etc. When the rubber composition is produced as a rubber cement, it can be prepared by dissolving the compound obtained as described above in an organic solvent. Dissolution is carried out using a planetary mixer, a stirrer, etc.

[0015] For example, the rubber composition can be used as a vibration-damping coating by containing an organic solvent. The rubber composition as a vibration-damping coating is applied to a desired substrate, and then dried to remove the organic solvent, thereby damping the vibration of the substrate and providing excellent adhesion to the substrate. The desired substrate is not particularly limited, but examples include automotive parts (e.g., heat-resistant parts for electric vehicles) and eAxles. [Example]

[0016] (Examples 1 to 10 and Comparative Examples 1 to 4) The components shown in Tables 1 and 2 below were kneaded to prepare rubber composition compounds. The rubber composition compounds obtained as described above were measured for the following properties.

[0017] (Vibration damping) In each of Examples 1 to 10 and Comparative Examples 1 to 4, a control sample was prepared so as to have the same composition except that it did not contain any layered or plate-like filler. The control sample was set in a capillary rheometer, and tan δ was measured under the following conditions. Temperature: 70℃ Frequency: 50Hz Twist angle: 1 degree Next, the rubber composition compounds prepared in Examples 1 to 10 and Comparative Examples 1 to 4 were set in a capillary rheometer in the same manner as the control sample, and tan δ was measured. Then, the rate of increase in tan δ was calculated using the following formula. (Rate of increase in tan δ) = (tan δ of each example) / (tan δ of the control sample of each example) In each example, the higher the calculated increase rate of tan δ, the better the vibration damping performance was evaluated.

[0018] (adhesion) A rubber paste was prepared by dissolving the rubber composition compound prepared by the above method in hexane (organic solvent). The rubber paste was applied to an aluminum substrate by spraying or the like, and then dried at 80°C for 10 minutes to obtain a coating film of the rubber composition. The resulting coating film was evaluated for adhesion by performing a cross-cut test evaluation according to JIS K5600 using the following procedures (1) to (3). (1) A grid-like pattern of cuts was made on the surface of the rubber composition with a cutter. (2) Cellophane tape was adhered to the surface of the rubber composition, and then the cellophane tape was peeled off. (3) The remaining state of the rubber composition on the substrate was confirmed, and the adhesion was evaluated on a scale of 0 to 5 according to the criteria in Table 3 below. The best adhesion was evaluated as 0 points, and the worst adhesion was evaluated as 5 points.

[0019] The film-forming properties of each example were evaluated as follows. (Film forming property) A rubber paste was prepared by dissolving the rubber composition compound prepared by the above method in hexane (organic solvent). The rubber paste was applied to an aluminum substrate by spraying or the like, and then dried at 80°C for 10 minutes to obtain a coating film of the rubber composition. The obtained coating film was rubbed with a finger, and if there was no dropout of filler or collapse of the film, it was judged to have good film-forming properties. The evaluation results for vibration-damping properties, adhesion and film-forming properties for each example are shown in Tables 1 and 2 below.

[0020] [Table 1]

[0021] [Table 2]

[0022] [Table 3]

[0023] The results in Tables 1 and 2 show that the rubber composition of the present invention provides excellent film-forming properties and vibration-damping properties, as well as good adhesion of 1 or less.

Claims

1. Butyl rubber, 50 to 500 parts by weight of a layer or plate-like filler relative to 100 parts by weight of the butyl rubber; Silane coupling agent A rubber composition comprising:

2. The rubber composition of claim 1 , wherein the butyl rubber is a halogenated butyl rubber.

3. 3. The rubber composition according to claim 1, wherein the layer-like or plate-like filler is mica or kaolin clay.

4. 3. The rubber composition according to claim 1, wherein the silane coupling agent is a silane coupling agent containing a vinyl group, an amino group, or an epoxy group.

5. The rubber composition according to claim 1 or 2, comprising 0.5 to 20 parts by weight of the silane coupling agent per 100 parts by weight of the butyl rubber.

6. 3. The rubber composition according to claim 1, further comprising an organic solvent, and having a solids concentration of 1 to 50% by weight.

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